It’s not hard to do a recompile with a slightly newer SDK, check things still work, update the version and copyright and re-upload. That’s how I keep all my apps in the store. Often you find a cheap update you ought to make, like add dark mode support which wasn’t a thing when the app was written. Sometimes you take the app across a tech boundary, like adding ARM code to a Mac app. I can see Apple’s motivation to keep fresh goods on their shelves that work with current OS versions and hardware.